Low profile motor

ABSTRACT

A low-profile motor includes a rotor yoke having a rotor magnet on its inner or outer surface and being rotationally supported on a motor base via a shaft, and a stator core constituted of a plurality of T-shaped winding parts each having an end opposed to the rotor magnet. On the motor base formed with a hole for supporting the rotor yoke via the shaft, the plurality of T-shaped winding parts are cut like tongues along the radial direction of the hole, and the T-shaped winding parts are each bent such that their ends are opposed to the rotor magnet. Thus, it is possible to readily form the T-shaped winding parts, eliminate the need for mounting the T-shaped winding parts, and reduce the number of parts and steps. This technique enables it to efficiently form an inexpensive low-profile motor for a magnetic disk unit and the like.

TECHNICAL FIELD

The present invention relates to a low-profile motor used for a magneticdisk unit and the like and a method of manufacturing the same.

BACKGROUND ART

As shown in FIG. 3, in a conventional low-profile motor used for amagnetic disk unit or the like, a rotator unit A is configured such thata rotor yoke 2 is fixed to a shaft 1 and a rotor magnet 3 are attachedto the inner surface of the rotor yoke 2. A bearing unit B isconstituted of a radial bearing 4 for supporting the shaft 1 in theradial direction and a thrust bearing 5 for supporting the shaft 1 inthe axial direction. The bearing unit B is fit and fixed into a hole 7 aof a cylindrical motor mounting part 7 which is formed on a motor base6, the inner edge of a stator core 8 is bonded and fixed to a step 7 bon the outer surface of the motor mounting part 7, and ends 9 a of aplurality of T-shaped winding parts 9 of the stator core 8 are opposedto the rotor magnets 3, respectively. With this configuration, byenergizing windings 10 on the T-shaped winding parts 9, a magnetic fieldis generated on the stator core 8, the rotor magnets 3 are excited, anda running torque can be generated on the rotor yoke 2.

As shown in FIG. 4, in the stator core 8, the T-shaped winding parts 9extend radially from a ring part fit onto the motor mounting part 7 andthe arc-shaped ends 9 a of the T-shaped winding parts 9 are arranged inthe circumferential direction. Conventionally, the stator core 8 isformed of a stack of stator plates. The stacking step and the step ofmounting the stator core 8 on the motor mounting part are complicatedand time consuming.

The present invention is devised to solve the problem and has as itsobject the provision of a low-profile motor in which a stator core canbe readily formed and mounted.

DISCLOSURE OF THE INVENTION

In order to attain the object, according to the first aspect of theinvention, a low-profile motor is provided, which comprises a rotor yokehaving a rotor magnet on its inner surface or outer surface and beingrotationally supported on a motor base via a shaft, and a stator coreconstituted of a plurality of winding parts each having an end opposedto the rotor magnet, wherein on the motor base where a hole forsupporting the rotor yoke via the shaft is formed, the plurality ofwinding parts constituting the stator core are cut like tongues alongthe radial direction of the hole and integrated, and each of the windingparts is bent such that the end of the winding part is opposed to therotor magnet. Thus, it is possible to readily form the winding parts ofthe stator core, eliminate the need for mounting the stator core, andreduce the number of parts and steps.

According to the second aspect of the invention, in the low-profilemotor configured as mentioned above, the motor base includes theplurality of winding parts is entirely formed of a silicon steel plate.Since the winding parts are integrated with the motor base, theelectrical characteristics of the winding parts constituting the statorcore is not impaired.

According to the third aspect of the invention, a manufacturing methodis provided for a low-profile motor which comprises a rotor yoke havinga rotor magnet on its inner surface or outer surface and beingrotationally supported on a motor base via a shaft, and a stator coreconstituted of a plurality of winding parts each having an end opposedto the rotor magnet. The method comprises forming on the motor base ahole for supporting the rotor yoke via the shaft, cutting the pluralityof winding parts constituting the stator core to be like tongues alongthe radial direction of the hole and integrating these winding parts onthe motor base, and bending each of the winding parts such that the endof each winding part is opposed to the rotor magnet. Hence, it ispossible to simplify the manufacturing process and achieve aninexpensive low-profile motor with high manufacturing efficiency ascompared with the conventional method of separately forming and mountinga stator core on a motor base.

According to the fourth aspect of the invention, in the method ofmanufacturing the low-profile motor mentioned above, the step of cuttingthe plurality of winding parts on the motor base and the step of bendingthe winding parts are performed by press processing. It is possible toperform the steps at once, thereby further simplifying the manufacturingprocess.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a low-profile motor of outer rotortype according to Embodiment 1 of the present invention;

FIG. 2 is a sectional view showing a low-profile motor of inner rotortype according to Embodiment 2 of the present invention;

FIG. 3 is a sectional view showing a conventional low-profile motor; and

FIG. 4 is plan view showing a conventionally used stator core.

BEST MODE FOR CARRYING OUT THE INVENTION

The following will describe embodiments of the present invention inaccordance with the accompanying drawings.

Embodiment 1

FIG. 1 is a sectional view showing a low-profile motor according toEmbodiment 1 of the present invention. In FIG. 1, members having thesame operations as those of the conventional low-profile motor shown inFIG. 3 will be indicated by the same reference numerals as FIG. 3.

As shown in FIG. 1, the low-profile motor is an outer rotor motor almostidentical in configuration to the conventional low-profile motor shownin FIG. 3. A rotator unit A is configured such that a rotor yoke 2 isfixed to a shaft 1 and rotor magnets 3 are attached to the inner surfaceof the rotor yoke 2. A bearing unit B is constituted of a radial bearing4 for supporting the shaft 1 in the radial direction and a thrustbearing 5 for supporting the shaft 1 in the axial direction.

The shaft 1 of the rotator unit A is inserted into the bearing unit Bwhich is fit and fixed into a hole 7 a of a cylindrical motor mountingpart 7 of a motor base 6. In the rotor yoke 2 of the rotator unit A, astator core 8 constituted of a plurality of T-shaped winding parts 9 isdisposed such that arc-shaped ends 9 a of the T-shaped winding parts 9are opposed to the rotor magnets 3. Windings 10 are wound aroundportions near the ends 9 a of the T-shaped winding parts 9.

The low-profile motor is different from the conventional motor in thatthe plurality of T-shaped winding parts 9 are cut like tongues along theradial direction of the motor mounting part 7 and integrally formed onthe motor base 6 where the cylindrical motor mounting part 7 is formedin the above manner, and the T-shaped winding parts 9 are bent likeletter L with the ends 9 a opposed to the rotor magnets 3. Openings 6 aformed by cutting and bending the T-shaped winding parts 9 are filledwith filling members 6 b.

To be specific, on a flat part of the motor base 6 extending from thelower end of the motor mounting part 7 to the outside, the T-shapedwinding parts 9 are cut to the inside along the radial direction of themotor mounting part 7 such that the ends 9 a are positioned near therotor magnets 3, and the T-shaped winding parts 9 are bent diagonallyabove at bent portions 9 b and bent to the outside at bent portions 9 c,so that the ends 9 a are opposed to the rotor magnets 3. The motor base6 including the T-shaped winding parts 9 is entirely formed of a siliconsteel plate which is used conventionally as a material of the statorcore 8.

In the production of the motor base 6, the cylindrical motor mountingpart 7 and the plurality of T-shaped winding parts 9 are sequentiallyformed in the flow of press processing for sheet metal (silicon steelplate). In this flow, the step of cutting the plurality of T-shapedwinding parts 9 like tongues and the step of bending the T-shapedwinding parts 9 can be performed at once.

Therefore, it is possible to reduce the number of components and stepsas compared with the conventional method of separately forming andmounting the stator core 8 on the motor base 6. Since the steps of thestator core make up a large proportion of the overall cost of the motor,the cost can be considerably reduced.

As described above, the motor base 6 including the T-shaped windingparts 9 is formed of a silicon steel plate, and thus the electricalcharacteristics of the T-shaped winding parts 9 constituting the statorcore 8 is not impaired.

Current low-profile motors have a limitation of storage up to about twostator plates having a thickness of 0.2 mm in a 1-inch HDD and so on.The low-profile motors can be further reduced in size and thicknessunlike the conventional art in which a stator core is formed of a stackof stator plates. In this case, the specification of windings is changedfrom that of a laminated stator core, so that the same characteristic asthe laminated stator core can be obtained.

Embodiment 2

FIG. 2 is a sectional view showing a low-profile motor according toEmbodiment 2 of the present invention. The low-profile motor is an innerrotor motor having the same configuration as the above-describedlow-profile motor. In the configuration of the low-profile motor,T-shaped winding parts 9 are cut to the outside along the radialdirection of a motor mounting part 7 on a flat part of a motor base 6such that ends 9 a of the T-shaped winding parts 9 are positioned nearrotor magnets 3, and each of the T-shaped winding parts 9 is bentdiagonally above at a bent portion 9 d and bent to the inside at a bentportion 9 e.

The shape of the motor mounting part 7 is not limited to a cylinder aslong as the motor mounting part 7 has a hole 7 a where a bearing unit Bcan be fit and fixed. In addition to the press processing, a method suchas metal injection is available to form the motor base 6.

As described above, in the low-profile motor of the present invention, aplurality of winding parts constituting a stator are cut and integrallyformed on a motor base, and the winding parts are bent such that theends of the winding parts are opposed to rotor magnets. Thus, it ispossible to achieve a small thickness, high manufacturing efficiency,and low cost as compared with the conventional art.

1. A low-profile motor, comprising: a motor base comprising a steel plate having a cylindrical motor mounting part and a stator core, such that the motor base, the cylindrical motor mounting part, and the stator core are integrally part of said steel plate, the motor base extending radially outward from the cylindrical motor mounting part past an outer edge of the stator core; a bearing located within said cylindrical motor mounting part; a rotator unit, comprising a rotor yoke attached to a shaft, said shaft rotationally supported by said bearing; and at least one rotor magnet attached to said rotor yoke; wherein the stator core comprises a plurality of winding parts that are integral with said motor base, the winding parts comprising portions of the steel plate defined by cuts in the motor base and still connected to the motor base at one end, the plurality of winding parts comprise tongues extending in a radial direction towards or away from said cylindrical motor mounting part, and the plurality of winding parts having radially extending ends not connected to said motor base, and opposite the rotor magnets.
 2. The low-profile motor according to claim 1, wherein the motor base is a single silicon steel plate. 